Beginning July 1, 2021 Android developers will be charged 15% of the first $1 million in digital sales through the Google Play app store for Android phones. Google takes 30% of sales after that.
Apple’s program is similar. As of Jan. 1, smaller companies can apply for a reduced fee of 15% from Apple. The total fee jumps back to 30% when the company surpasses $1 million in App Store sales.
Steam still wants $100 to buy into the Store. Then the 30% fee is still imposed. The Valve engine is available for free which has easy system requirements.